Package jcckit.util

Class FlatConfigData

java.lang.Object
jcckit.util.FlatConfigData
All Implemented Interfaces:
ConfigData
Direct Known Subclasses:
AppletBasedConfigData, PropertiesBasedConfigData
public abstract class FlatConfigData extends Object implements ConfigData
An implementation of ConfigData based on a flat representation of the hierachically organized key-value pairs. Concrete subclasses must implement the methods getValue(java.lang.String) and createConfigData(java.lang.String) in accordance with the Template Method pattern and Factory Method pattern, respectively.

In a flat representation of hierachically organized key-value pairs all key-value pairs are stored in a single Hashtable. Its key is the full key of the configuration data (i.e. the key including its path).

Example (using the notation for a .properties file): 

  title = example
  symbolAttributes/className = jcckit.graphic.BasicDrawingAttributes
  symbolAttributes/fillColor = 0xcaffee
  symbolAttributes/lineColor = 0xff0000
The following table shows the result of some method calls at a FlatConfigData instance prepared with this example:

Method callResult
get("title")example
getNode("symbolAttributes").get("fillColor") 0xcaffee

In addition FlatConfigData implements inheritance of key-value pairs. Basically a node in the tree of key-value pairs may extend another node in the tree. The extended node inherit all key-value pairs from the extending one including the key-value pairs of all descendants. The value of a inherited key-value pair may be overridden. Also new key-value pairs may be placed in the inherited node or anywhere in the subtree. Note, that the extending node has to be a node which is not a descendant of the extended node (otherwise a circulary chain of references occurs). As a consequence not more than 20 inheritance levels are allowed.

The implementation of this kind of inheritance in a flat hashtable is done by an additional key-value pair of the form 

    extending-node/ = extended-node/
Example: 
  A/a/priority = high
  A/a/alpha/hello = universe
  A/a/alpha/answer = 42
  A/b/1/ = A/a/
  A/b/1/alpha/hello = world
  A/b/1/alpha/question = 6 * 7
The following table shows the result of various method calls applied at the node A/b/1/ of a FlatConfigData instance prepared with this example:

Method callResultComment
get("priority")highinherited
getNode("alpha").get("hello") worldoverridden
getNode("alpha").get("question") 6 * 7added
getNode("alpha").get("answer") 42inherited

  • Constructor Details

    • FlatConfigData

      public FlatConfigData(String path)
      Creates a new instance for the specified path.

  • Method Details

    • getFullKey

      public String getFullKey(String key)
      Returns the full key.
      Specified by:
      getFullKey in interface ConfigData
      Parameters:
      key - A (relative) key. null is not allowed.
      Returns:
      the path concatenated with key or key if the path is undefined.

    • get

      public String get(String key)
      Returns the value associated with this key.
      Specified by:
      get in interface ConfigData
      Parameters:
      key - The relative key. null is not allowed.
      Returns:
      the associated value. Will be null if no value exists for key.

    • getNode

      public ConfigData getNode(String key)
      Returns the ConfigData object associated with this key.
      Specified by:
      getNode in interface ConfigData
      Parameters:
      key - The relative key.
      Returns:
      the associated value. Will never return null. Instead an empty ConfigData is returned.

    • getValue

      protected abstract String getValue(String fullKey)
      Returns the value for the specified full key from the flat representation of the hierarchically organized key-value pairs.
      Parameters:
      fullKey - The full key including path. null is not allowed.
      Returns:
      the value or null if not found.

    • createConfigData

      protected abstract ConfigData createConfigData(String path)
      Returns the FlatConfigData object for the specified full path. In general path will be used in the constructor with path argument.
      Parameters:
      path - The full path.
      Returns:
      a new instance in any case.